Intermediate Transfer Belt for Duplex Digital Printing
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Solution Overview
Problem
Existing digital printing technologies face challenges in achieving high-quality images on substrates due to inkjet printing limitations, such as wicking, poor image quality, and difficulties in duplex printing, especially with fibrous materials like paper, which require costly substrate coatings and additional drying steps.
Innovation Solution
A printing system utilizing a flexible, substantially inextensible belt as an intermediate transfer member with a drying station and dual impression stations allows for consistent ink transfer and drying, enabling high-quality printing on both sides of a substrate without substrate wetting, using a thin belt and a compressible blanket for conformability and efficient energy use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If inkjet printing is used directly onto porous paper substrates, then the printing process is simple, but the image quality deteriorates due to wicking and variation in distance between print head and substrate surface
Solution Approach 1:
The patent introduces an intermediate transfer member (belt) that receives ink droplets from the inkjet print head and transfers them to the substrate. This mediator maintains a constant distance between the print head and the transfer member surface, eliminating the wicking problem and distance variation issues that occur when printing directly onto porous substrates. The belt acts as a buffer that decouples the printing process from substrate properties.
2Manufacturing precision
If substrate coatings are used to control ink absorption, then image quality improves, but the cost increases and additional drying steps are required
Solution Approach 1:
The intermediate transfer member belt provides a controlled surface for ink transfer that eliminates the need for specialized substrate coatings. The belt's surface properties are optimized for ink reception and transfer, allowing standard substrates to be used without expensive coatings or additional drying steps.
Solution Approach 2:
The system performs preliminary drying of the ink image on the intermediate transfer member belt before transfer to the substrate. This preliminary action removes the need for post-printing drying steps and eliminates the risk of ink smearing during substrate handling.
3Ease of operation
If excessive wetting of substrate is avoided, then handling and stacking improve, but the ink transfer efficiency may deteriorate
Solution Approach 1:
The intermediate transfer member belt allows the ink to be transferred in a controlled manner, providing sufficient contact time and pressure for efficient ink transfer without excessive wetting of the substrate. The belt mediates between the ink source and substrate, optimizing the transfer process.
Solution Approach 2:
The system uses dynamic control of the pressure cylinder and blanket to optimize ink transfer. The pressure is applied only when needed during the transfer process, and the blanket is compressed to ensure good contact between the belt and substrate, maximizing transfer efficiency while controlling wetting.
4Productivity
If silicone coated transfer members are used to facilitate image transfer, then transfer efficiency improves, but ink droplet beading occurs making drying more difficult
Solution Approach 1:
The patent modifies the surface properties of the intermediate transfer member belt to balance ink reception and transfer characteristics. By adjusting the surface energy and wettability parameters of the belt, the system achieves good ink droplet contact for efficient drying while maintaining effective ink transfer to the substrate.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This system enhances image quality and efficiency by maintaining a constant distance for ink transfer, reducing substrate wetting, and allowing for rapid image drying, enabling cost-effective duplex printing without the need for specialized substrates, while minimizing energy consumption and extending component lifespan.
Implementation Method 1
a drying station for drying the ink image on the belt to leave an ink residue film on the outer surface of the belt
Implementation Method 2
a pressure cylinder carrying a compressible blanket for urging the belt against the substrate supported on the impression cylinder
Data Source
AI summary
A printing system for printing on a substrate, comprises a movable intermediate transfer member in the form of a flexible, substantially inextensible, belt guided to follow a closed path, an image forming station for depositing droplets of a liquid ink onto an outer surface of the belt to form an ink image, a drying station for drying the ink image on the belt to leave an ink residue film on the outer surface of the belt, first and second impression stations spaced from one another in the direction of movement of the belt, each impression station comprising an impression cylinder for supporting and transporting the substrate and a pressure cylinder carrying a compressible blanket for urging the belt against the substrate supported on the impression cylinder, and a transport system for transporting the substrate from the first impression station to the second impression station.The pressure cylinder of at least the first impression station is movable between a first position in which the belt is urged towards the impression cylinder to cause the residue film on the outer surface of the belt to be transferred onto the front side of the substrate supported on the impression cylinder, and a second position in which the belt is spaced from the impression cylinder to allow the ink image on the belt to pass through the first impression station and arrive intact at the second impression station for transfer onto the reverse side of the substrate supported on the second impression cylinder.